Master of Science

thesisThe focus of this thesis is the impact and use of crosstalk and coupling when testing for electrical wiring faults using reflectometry. This thesis describes a method for detecting and locating faults on cable shields using an adapted reflectometry system. A signal transmitted on the inner conductor is coupled to the outside through the fault, a small aperture in the cable shielding. This very small signal is then detected and correlated with the original signal transmitted on the inner conductor. The signals that leak out of the aperture, the damaged shield, and propagate down the outside of the cable are quantified as a function of the aperture size and frequency. A ferrite loaded toroidal sensor design is also proposed for receiving this external signal in order to both detect and localize the shield damage. Both simulations and measurements validate the effectiveness of this method. Unshielded discrete wires are another common type of transmission line. While unshielded wires are primarily used for DC power, they are still subject to degradation over time and require maintenance. Unlike shielded cables, there is a significant amount of coupling that occurs between adjacent wires during a reflectometry test. This coupling is quantified and evaluated for two applications. The first is simultaneous testing of multiple adjacent wires in a bundle. In this case, minimizing the coupling is desirable in order to reduce noise in the reflectometry signature. The second is the exploration of the potential for a single reflectometry test to locate faults on adjacent wires without directly testing them. When a single test is performed in a multiwire bundle, the reflectometry signature will be a superposition of reflections from all nearby conductors. This thesis addresses the testing of a multiconductor wiring structure with a common signal reference as well as a similar structure with an isolated signal reference. In order to accurately detect faults on multiconductor wiring structures, both testing methods must be considered. A fault between a conductor and its reference conductor is easily detectable. A cross fault between two nonreference conductors is not. For cross fault consideration, the only method for detection is using a common signal reference and analyzing the data on adjacent lines

Design methodology and productivity improvement in high speed VLSI circuits

2017 Spring.Includes bibliographical references.To view the abstract, please see the full text of the document

Impulse TDR and its Application to Characterisation of Antennas

Passive microwave systems are traditionally characterised in the frequency-domain with a vector network analyser (VNA). The measurement of antennas typically takes place in an anechoic chamber where the interference from spurious reflections and outside noise is minimised. Despite the high level of accuracy achieved with this approach, such facilities have high costs associated with them. Recent publications have demonstrated the characterisation of antennas using a step-function time domain reflectometer (TDR) along with frequency-domain processing techniques. Localisation of the measurement in time prior to transformation allows for the dismissal of unwanted spurious reflections, eliminating the need for an anechoic chamber. An alternative technique is proposed whereby an impulse generator is employed in place of the step generator in a TDR. The advantage conferred by "impulse TDR" (ITDR) is that more energy is available at higher frequencies than with conventional step TDR, leading to a higher bandwidth and signal-to-noise ratio (SNR). The theoretical result is compared with measurement

Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Continuous-Time and Companding Digital Signal Processors Using Adaptivity and Asynchronous Techniques

The fully synchronous approach has been the norm for digital signal processors (DSPs) for many decades. Due to its simplicity, the classical DSP structure has been used in many applications. However, due to its rigid discrete-time operation, a classical DSP has limited efficiency or inadequate resolution for some emerging applications, such as processing of multimedia and biological signals. This thesis proposes fundamentally new approaches to designing DSPs, which are different from the classical scheme. The defining characteristic of all new DSPs examined in this thesis is the notion of "adaptivity" or "adaptability." Adaptive DSPs dynamically change their behavior to adjust to some property of their input stream, for example the rate of change of the input. This thesis presents both enhancements to existing adaptive DSPs, as well as new adaptive DSPs. The main class of DSPs that are examined throughout the thesis are continuous-time (CT) DSPs. CT DSPs are clock-less and event-driven; they naturally adapt their activity and power consumption to the rate of their inputs. The absence of a clock also provides a complete avoidance of aliasing in the frequency domain, hence improved signal fidelity. The core of this thesis deals with the complete and systematic design of a truly general-purpose CT DSP. A scalable design methodology for CT DSPs is presented. This leads to the main contribution of this thesis, namely a new CT DSP chip. This chip is the first general-purpose CT DSP chip, able to process many different classes of CT and synchronous signals. The chip has the property of handling various types of signals, i.e. various different digital modulations, both synchronous and asynchronous, without requiring any reconfiguration; such property is presented for the first time CT DSPs and is impossible for classical DSPs. As opposed to previous CT DSPs, which were limited to using only one type of digital format, and whose design was hard to scale for different bandwidths and bit-widths, this chip has a formal, robust and scalable design, due to the systematic usage of asynchronous design techniques. The second contribution of this thesis is a complete methodology to design adaptive delay lines. In particular, it is shown how to make the granularity, i.e. the number of stages, adaptive in a real-time delay line. Adaptive granularity brings about a significant improvement in the line's power consumption, up to 70% as reported by simulations on two design examples. This enhancement can have a direct large power impact on any CT DSP, since a delay line consumes the majority of a CT DSP's power. The robust methodology presented in this thesis allows safe dynamic reconfiguration of the line's granularity, on-the-fly and according to the input traffic. As a final contribution, the thesis also examines two additional DSPs: one operating the CT domain and one using the companding technique. The former operates only on level-crossing samples; the proposed methodology shows a potential for high-quality outputs by using a complex interpolation function. Finally, a companding DSP is presented for MPEG audio. Companding DSPs adapt their dynamic range to the amplitude of their input; the resulting can offer high-quality outputs even for small inputs. By applying companding to MPEG DSPs, it is shown how the DSP distortion can be made almost inaudible, without requiring complex arithmetic hardware